There is no single answer to sort questions. The best solution depends on your data. The data that you show will sort correctly with perl's default sort. This is probably not what you want because it is only sure of working correctly if the numbers in col 1 have only one digit.

Chris's solution is excellent. It will work for any number, but each number must be unique.

An even more general solution is the "Schwartzian Transform". Refer to the FAQ "How do I sort an array" Good Luck, Bill